Tehran, Mar 7 (IANS): Iran's supreme leader on Sunday called for the development of renewable and clean energy resources, such as civilian nuclear energy, in the country to substitute fossil fuels.

Ayatollah Seyyed Ali Khamenei made the remarks after he planted saplings to mark Iran's National Arbor Day and Natural Resources Week, Xinhua news agency reported, citing the leader's official website.

The leader described the development of non-fossil fuels, such as nuclear energy, as a growing trend around the globe, saying regional countries are also working toward the goal.

He urged for paying serious attention to the development of renewable energy resources such as solar and wind power, which are more environmentally friendly, calling on the Energy Ministry and other related organisations to play their roles in this regard.

On Arbor Day, which fell on March 6 this year, Iranian officials, individuals, groups and environmental activists plant trees and encourage others to do so.

Iran claims it has been working on a peaceful nuclear program over the past years, with a focus on electricity generation and medicinal applications. The United States and some countries have blocked Iran's efforts by imposing sanctions and accusing Tehran of seeking nuclear weapons.

Iran has repeatedly denied these accusations, claiming that it has no intention of exploiting nuclear power for military purposes.